Fluorescent lamps give more lumens of light per watt of electricity than incandescent lamps. So they have replaced incandescents in many fields, and hundreds of millions of installations are in use throughout the world. After World War II, a decline in the overall cost of fluorescent lighting caused it to be used freely at substantial foot candle levels in offices, stores and factories. However, the abrupt rise in the cost of energy in the early 1970's caused building managers, illumination engineers and architects to re-think the amount of light needed for various activities. What were previously deemed desireable levels of lighting now seemed lavish and too costly. Buildings that had been planned before the energy crunch were being described as "over-lamped". And ways were being sought to reduce the electrical consumption even if the previous lighting levels had to be sacrificed. And to some degree, at least, lighting levels could be reduced without harm, as in corridors and work areas where local task lighting could supplement a lower general light level. All at a reduction in electrical load.
To meet these changed conditions, lamp manufacturers developed lamps with somewhat lower wattage to work with existing ballasts. And ballast manufacturers brought out energy saving ballasts for new fixtures or replacement. Phantom tubes were invented that enable one lightable lamp to be removed from a two lamp fixture with a saving in power.
At the present time, another great set of problems has arisen in the energy industry. Although the cost of fuels has leveled off---even declined at least for some indefinite period---the cost of expanding power plant capacity has become almost prohibitive. Important factors being:
1. Public opposition to nuclear power plants has delayed their construction while fixed costs such as interest on financing continue, delays or not.
2. Fossil fuel plants, both existing and planned, are being forced by law to reduce stack emissions, often at great expense. Although this is socially desireable, it discourages expansion of power producing capacity.
3. Demand by consumers for reasonably priced electricity continues to rise, especially for air conditioning which causes extreme peak loads on hot days.
4. To carry short-time peak loads, many power plants have added gas turbine generators. Simple to install and noted for rapid start-up compared to steam plants, they are ideal for this service. But their higher fuel cost makes them too expensive to carry the base load at which large steam plants still excel. In many areas, this "fix" has been carried as far as practical.
So now, conservation is again being sought to bring electrical consumption more into line with the capacity of existing power systems. In many parts of the United States, cash incentives are being given by power companies, both public and investorowned, to consumers for installing power conserving devices. Some such plans pay for each energy reducing fluorescent tube or ballast that replaces a standard tube or ballast. Others offer rebates per kilowatt-hour for the rated life of energy saving equipment.
The invention here is such an energy-saving device and can save a building management approximately half the electrical power normally used for every fluorescent light fixture so fitted, in addition to the incentives that might be offered by the power company for the conversion. The reduced heat output of the fixtures can also save on the building air conditioning load. It does this without the shortened life of lamps or ballast experienced with similar devices in the prior art. And the conversion is as simple as relamping existing fixtures.
Even though the amount of power saved in one fluorescent fixture is small, when multiplied by even a small percentage of existing fixtures, the total saving in a large building and to the country can be great. So by the use of this device, consumers are benefited, power companies in their present situation are benefited, and the environment is helped by holding emissions to present levels, all in proportion to the number of phantom tubes in use.